The objective of this research project is to study the mechanism of regulation of RNA synthesis in nucleated cells. The experimental approach focuses on the role of the protein synthetic machinery in controlling the RNA synthetic machinery. By exploring the coupling and uncoupling of protein and RNA synthesis, it is expected that the factor(s) controlling the synthesis of RNA will be found. Two nucleated systems will be used; one is the yeast system, which is a low eukaryote, in which the protein synthetic machinery can be suppressed when thermo- sensitive mutants are cultured at the non-permissive temperature (36 degrees). This provides a method for inhibiting protein synthesis without the use of drugs such as cycloheximide. The other system is ascites cells, one of the few cancer cells in which RNA synthesis can be suppressed by amino acid starvation. In addition, synchronization of the latter will provide information about the control of RNA synthesis in relation to the different stages of the cell cycle. The assay for the factors will be made in two cell-free systems -- one using the natural template of the isolated yeast and ascites cell's nuclei and the other using synthetic homopolymers and copolymers with the purified RNA polymerases. Nuclear and cytoplasmic extracts will be added to both systems. These extracts will be obtained from starved and non-starved cells as well as cells in which protein synthesis has been inhibited by other means. In addition, extracts will be obtained from cells in M, G1, S, and G2 phases. The effect of these extracts on RNA chain initiation and elongation will be assayed. When the appropriate conditions of detection of the factors are established, isolation and characterization will be attempted.